1. Field of the Invention
The invention relates to circuit elements formed, by a novel process, in a continuous run or band of polysilicon material established on the surface of a semiconductor wafer and more particularly to a memory cell in which a series arrangement of a load resistor and the gate electrode of a self-aligned insulated silicon gate field effect semiconductor device and a conductive connection therebetween are all formed as corresponding portions of a single common monolithic polysilicon run, as well as conductive connections to a voltage supply point and to the active areas (such as source and drain areas) of other field effect devices.
2. Description of the Prior Art
In the prior art, it is well known to fabricate monolithic memory cells employing FET switching devices having metal gate electrodes connected to polysilicon load resistors. Such memory systems have been constructed and sold by the assignee of the present application. The construction of such systems is very complex requiring a large number of masking steps and does not provide any of the known advantages of self-aligned insulated silicon gate FET devices for conserving wafer or chip area and providing high uniformity of device performance.
There are two publications which are not prior art to the present applicants' invention but which are, nevertheless, of interest because they mention memory cells having ion-implanted polysilicon load resistors. These publications are: (1) the paper entitled "A5V-Only 4-K Static Ram" by McKenney printed at page 16 of the Digest of Technical papers of the 1977 IEEE Solid State Circuits Conference and bearing a date of Feb. 16, 1977, and (2) the article entitled "Uncompromising 4K-Static RAM Runs Fast on Little Power" by Sam Young, published in Electronics Magazine (May 12, 1977 issue). Both publications indicate that the polysilicon load resistors of the cell are formed using ion implantation but do not, apparently by intention, provide further information concerning the process of formation or the overall structure formed. In any event, the present applicants' invention substantially precedes the dates of these publications.